How to emit only one hair particle from each vertex?
You absolutely can.
Make particles come from verts, uncheck &quot;random order&quot; and input on the &quot;number&quot; the exact number of vertexes you object has.
8 in the case of a cube.
Crazy shape? No problem!

Just match verts and number of hairs.
Wanna use a collection of objects? No problem!
Just make sure the origins are all consistent.